As medical containers such as bags for infusions, medial solutions, and the like, soft bags made of polyethylene, polypropylene, polyvinyl chloride, or the like into a bag by blow molding or heat sealing, are used in addition to glass bottles of the related art. Since such soft bags are light-weighted, have small volumes when the bags are disposed, and even do not require ventilation needles that cause nosocomial infection occurring during administration, soft bags are mainstream.
A film used in the soft bags of the related art is composed of a polyolefin material including polyethylene, polypropylene, or the like in order to reduce amount of eluted materials in steam autoclaving, and maintain transparency and flexibility of the film. For this reason, a bag-making process by external heating such as heat sealing is conducted with caution for some period of time so that the surface of the film is not damaged.
For the purpose of reducing the damage on the film subjected to external heating in steam autoclaving, various inventions have been attained in which a heat resistant material is arranged in the external layer.
For example, Patent Document 1 discloses that an oriented polyamide film, an oriented polypropylene film, or an oriented polyethylene terephthalate film is arranged in the external layer, an anchor agent is applied on the inner surface, and then an adhesive resin is laminated. However, 0.05 to 1 g/m2 of an organic solvent with a urethane base, an imine base, or the like is applied as the anchor agent. The figures are within the elution test specifications defined by Japanese Pharmacopoeia, and however the amount of eluted material cannot be negligible. Furthermore, since extrusion or sandwich lamination has to be gone through, incorporation of foreign substances into an exposed lamination interface is a concern.
Patent Document 2, for example, discloses a laminated body in which a polyamide film having a heat resistance property is arranged. Since the laminated body is designed with the main object of giving a gas barrier property thereto, and is not the outermost layer, it is slightly effective at reducing damage on the film when the film is made into a bag. Furthermore, since such inventions use the dry lamination method that uses an organic solvent-based adhesive, there is the same concern as in above-described Patent Document 1.